Oligodendrocytes (OLs) are myelinating glial cells that form myelin sheaths around axons to ensure rapid and focal conduction of action potentials.Here,we found that an axonal outgrowth regulatory molecule,AATYK (apoptosis-associated tyrosine kinase),was up-regulated with OL differentiation and remyelination.We therefore studied its role in OL differentiation.The results showed that AATYK knockdown inhibited OL differentiation and the expression of myelin genes in vitro.Moreover,AATYK-deficiency maintained the proliferation status of OLs but did not affect their survival.Thus,AATYK is essential for the differentiation of OLs.